8.4.6.8.2 Deactivation Procedure

The QSPI deactivation procedure is as follows.

1. Wait for QSPI_SR.RBUSY=0 and QSPI_SR.HIDLE=1.
2. Send a QSPI_CR.LASTXFER command.
3. Wait for QSPI_ISR.CSRA=1.
4. Set QSPI_CR.QSPIDIS and wait for QSPI_SR.QSPIENS=0.
5. Disable the GCLK clock.
6. Disable the peripheral clock.